An image forming device including: an image forming unit; a heating body; a power supply unit; a temperature sensing member; and a controller. The image forming unit is configured to form an image on a recording sheet. The heating body is configured to heat the recording sheet on which the image is formed. The power supply unit is configured to supply power to the heating body. The temperature sensing member is configured to detect a temperature of the heating body. The controller is configured to: control the power supply unit based on the detected temperature; determine whether or not a high-power output state of the power supply unit has continued for a first duration under a print control process; and judge that the temperature sensing member is in an abnormal state when determination is made so that the high-power output state has continued for the first duration.